Unfortunately many of the pranks we got up to were rather less good-natured as we got older and more anarchic. The film If was a major influence and we started getting into explosives in quite a major way.
Our sixth form house was a rambling old detached house in the school grounds with a terrace or loggia with a parapet, and I would lounge sullenly on the parapet in an old Army greatcoat trying to read while my best friend did his best to rag me. The crowning glory was when he lobbed a blast bomb at me - a cigar tube filled with talc and a bit of nitro-cellulose - which missed and carthweeled over the ballustrade and down to the fire pool below, where a small knot of squeaking 12-year-olds were being shown where the newts lived
The blast bomb detonated about an inch above the water, soaking and terrifying both the kids and the very new female biology teacher. That was another uncomfortable interview with the house-master and yet another threat of expulsion.
We carried on with the bombs, but with more discretion, trying them out in local woods and over on the sports pitches. Amazingly I've still got both eyes and 10 fingers.
Then there was the time we went down into the bowels of the house and found half a dozen ancient air rifles which had clearly once been used for the shooting gallery at summer fetes and things. These were smuggled out in cricket bags and used for earnest training missions of the with home-made grenades in the local woods, only to be themselves "liberated" by some local kids from where we'd cached them.
Charming little sods, we were!